The techniques disclosed herein relate to optical components. The techniques disclosed herein particularly relate to optical components whose surface is provided with an antireflection structure for reducing reflection of incident light.
In recent years, various types of optical components whose surface is provided with an antireflection treatment for reducing light reflection have been suggested.
Examples of the antireflection treatment include forming fine structures on a surface of the optical component with a pitch equal to or smaller than the wavelength of the incident light. For example, the fine structures may be made of linear raised portions or linear recessed portions which are periodically arranged, or may be made of cone-shaped or columnar raised portions, or funnel-shaped or cylindrical recessed portions which are periodically arranged. Hereinafter, a structure in which a plurality of such fine structures are arranged may be referred to as a “antireflection structure” or a “subwavelength structure (SWS).”
For example, Japanese Patent Publication No. 2005-283814 discloses an optical element in which the asperities of the antireflection structure are arranged in a descending order of depth toward the outer periphery.